john-okeefe
46ae45ee92
Vendored the sevenzip package to eliminate dependency chain: - sevenzip -> go4.org -> 25+ Google/Cloud/telemetry packages Changes: - Added internal/sevenzip/ with full package source - Inlined go4.org/readerutil into multireaderat.go - Updated all internal imports to use bookhoard/internal/sevenzip - Preserved .cb7 comic archive support This reduces bloat by ~4.9 MB and removes unused telemetry dependencies while maintaining all functionality.
105 lines
1.6 KiB
Go
105 lines
1.6 KiB
Go
package bra
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import (
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"encoding/binary"
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"io"
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)
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const bcjLookAhead = 4
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type bcj struct {
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ip, state uint32
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}
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func (c *bcj) Size() int { return bcjLookAhead + 1 }
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func test86MSByte(b byte) bool {
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return (b+1)&0xfe == 0
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}
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//nolint:cyclop,funlen,gocognit
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func (c *bcj) Convert(b []byte, encoding bool) int {
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if len(b) < c.Size() {
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return 0
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}
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var (
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pos uint32
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mask = c.state & 7
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)
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for {
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p := pos
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for ; int(p) < len(b)-bcjLookAhead; p++ {
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if b[p]&0xfe == 0xe8 {
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break
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}
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}
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d := p - pos
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pos = p
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if int(p) >= len(b)-bcjLookAhead {
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if d > 2 {
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c.state = 0
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} else {
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c.state = mask >> d
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}
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c.ip += pos
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return int(pos)
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}
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if d > 2 {
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mask = 0
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} else {
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mask >>= d
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if mask != 0 && (mask > 4 || mask == 3 || test86MSByte(b[p+(mask>>1)+1])) {
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mask = (mask >> 1) | 4
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pos++
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continue
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}
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}
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//nolint:nestif
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if test86MSByte(b[p+4]) {
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v := binary.LittleEndian.Uint32(b[p+1:])
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cur := c.ip + uint32(c.Size()) + pos //nolint:gosec
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pos += uint32(c.Size()) //nolint:gosec
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if encoding {
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v += cur
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} else {
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v -= cur
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}
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if mask != 0 {
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sh := mask & 6 << 2
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if test86MSByte(byte(v >> sh)) {
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v ^= (uint32(0x100) << sh) - 1
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if encoding {
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v += cur
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} else {
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v -= cur
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}
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}
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mask = 0
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}
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binary.LittleEndian.PutUint32(b[p+1:], v)
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b[p+4] = 0 - b[p+4]&1
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} else {
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mask = (mask >> 1) | 4
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pos++
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}
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}
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}
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// NewBCJReader returns a new BCJ io.ReadCloser.
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func NewBCJReader(_ []byte, _ uint64, readers []io.ReadCloser) (io.ReadCloser, error) {
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return newReader(readers, new(bcj))
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}
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